How did GenX-related chemicals get in OWASA water, Jordan Lake? Scientist has theory.

A Duke University scientist thinks cleaners, clothing and other products that people use may be feeding GenX-related chemicals into Jordan Lake and its feeder streams.

The results are preliminary and based on small samples, but Nicholas School of the Environment professors Heather Stapleton and Lee Ferguson recently reported finding detectable levels of nine “perfluorinated chemicals” in water from Jordan Lake and in Cary, Chapel Hill and Durham tap water.

Perfluorinated chemicals are designated as short- or long-chain, depending on their number of carbon molecules. They have been around longer than GenX and have many industrial applications, from firefighting foams to nonstick coatings — think Teflon — as well as cleaners and water- and stain-resistant textiles.

Attention recently was drawn to GenX, used to make Teflon and other coatings, after the chemical was found in Wilmington’s chief water supply.

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“Every time you wash your clothes, you have these dust particles that just come off your clothes and down through the drain, and go into the wastewater treatment plant,” Stapleton said.

“I have a feeling that what’s happening is there’s a large number of these coming through the wastewater treatment plant and just not being effectively removed, and ending up going right into the effluent, which enters Lake Jordan,” she said. “And because the lake waters are so low right now because of the drought, I think it’s having a concentration effect.”

Cary water officials have talked with the scientists about their samples, which showed the tested chemicals together exceeded 200 parts per trillion (ppt).

They’ll meet soon with Orange Water and Sewer Authority officials about the Chapel Hill samples, OWASA sustainability manager Mary Tiger said. OWASA’s staff, because of the holidays, has not had the time to examine the data, she said.

“We take it very seriously, and we are pulling together a plan that will be informed by this meeting with the professors, as well as consultations with neighboring communities and the state and other stakeholders,” Tiger said.

“OWASA has a positive working relationship with the university and has been assured when we have visited labs that faculty, staff, and students are well-trained on what not to put down the drain,” Tiger said.

The water sample drawn from Morgan Creek, a few miles south of OWASA’s wastewater treatment plant, had a combined PFOA/PFOS level of 26 ppt and a total level of 115 ppt for all nine chemicals. Chapel Hill’s tap water measured “significantly lower than what we found in the town of Cary,” Stapleton said.

An OWASA employee checks one of the treatment tanks at the Mason Farm Wastewater Treatment Plant on Morgan Creek in southeastern Chapel Hill. Duke scientists found perfluorinated chemicals in a water sample taken from the creek near the Farrington Mill Road bridge, a few miles south of the plant.

OWASA Contributed

The EPA threshold for combined PFOA/PFOS levels is 70 ppt, or about 70 drops in 10 million gallons of water. The EPA has not established a health level for seven other PFCs included in the test, Stapleton said.

Durham County’s levels were below 14 ppt, consistent with stricter standards that some states, such as New Jersey, have set for themselves.

While most utilities filter wastewater using activated carbon, which works well for long-chain chemicals, Stapleton said that’s not the best way to treat short-chain types. That may be why those chemicals appeared at high levels in their water samples, she said.

“Something like reverse osmosis would remove it, so that’s something that people could consider for their home,” Stapleton said. “I don’t think there’s an opportunity for (those systems), at least at this point, to be made commercial for large utilities.”

OWASA tested four times for six different PFCs and found one sample high enough to meet the combined PFOA/PFOS level. It’s not clear why that sample was at a detectable level, Tiger said. The EPA studied the data before issuing health advisories for PFOA and PFOS levels in 2016.

Long-chain chemicals, like PFOA and PFOS, get more attention because of how they build up in the body and may affect reproduction and development. While the EPA considers short-chain chemicals less toxic, Stapleton said that doesn’t mean everything’s fine, because the data about possible health effects is limited.

It takes years – once you stop consuming perfluorinated chemicals – for the body to shed them, she said, noting the risk could be even higher for young children.

“Just because we don’t currently have any data suggesting they could be bad for us doesn’t mean we shouldn’t be concerned,” Stapleton said. “We should still be trying to do something to remove them from our drinking water. I don’t hear any discussions about that, which is unfortunate.”